1. Field of the Invention
The present invention relates to a display device, and more particularly, to a bias circuit and a method for operating the same for a display device, e.g., cathode ray tube (CRT) and preferably, an ultra slim display device.
2. Background of the Related Art
A cathode ray tube (CRT) of a display device focuses and accelerates electrons discharged from an R/G/B electron gun, which collide with an R/G/B phosphor screen through a shadow mask to form pixels. An electrical current flows through vertical and horizontal bias coils to create a 2-dimensional screen. However, a picture distortion may occur caused by a difference in the distance between the electron gun and a center portion of the CRT screen and the difference in distance between the electron gun and corner portions of the CRT screen. In other words, since the distance between the electron gun and the corner portions of the CRT screen is relatively long, a cross-hatch width on the screen may not be uniform, and the resolution (or definition) at the corner portions of the screen may be lower than the resolution (or definition) at the center portion of the screen.
Further, due to the above-described difference in distance, a pin distortion may occur at the corner portions of the screen. As the distance between the electron gun and the CRT screen becomes smaller, the above-described picture distortion may worsen. Hence, there are many difficulties including ones described above for reducing the distance between the electron gun and the CRT screen and difficulties in producing an ultra-slim display device especially, an ultra-slim CRT display device.